Vandal resistant display units

ABSTRACT

A display device includes a component in the form of a plate bearing one or more display indicia on one plate surface and having a passage extending through the plate adjacent the display indicium. An integral light-transmissive element is fixedly secured in the plate passage and has a first lensed surface at one end adjacent the display indicium. At its opposite end, the light-transmissive element defines both a second lensed surface and a flat surface in abutting relation to a stepped part of the passage within the plate. The first lensed surface is convex relative to the light-transmissive element and the second lensed surface is concave relative to the light-transmissive element. The element, comprised of a polycarbonate film which is highly resistant to impact damage, is of dimension relative to the passage such that an interference-fit exists therebetween. The element is accordingly not removable by action thereon at the display surface, is not destructed by impact and cannot be forced against an interior light source, thereby providing a quite high degree of resistance to vandalism.

FIELD OF THE INVENTION

This invention relates generally to the illuminated display field andpertains more particularly to vandal-resistant illuminated displayunits.

BACKGROUND OF THE INVENTION

The illuminated display field, has in recent years, been impactedadversely by vandalism and related destructive activity, which hasspawned an effort to provide what might be termed "vandal-resistant"display units.

Relatively simple destructive activity renders typical presentlycommercialized displays unusable. By way of example, elevator up/downindication is generally provided by an indirectly lit epoxy display in ametal plate adjacent the elevator station. The plate supports anelevator call button and the user is accomodated by prompt illuminationof the epoxy display upon pressing the call bottom, which activates alamp supported interiorly of the plate. Insertion of virtually any toolor sharp object into the epoxy display destroys the display and callsfor full plate replacement.

SUMMARY OF THE INVENTION

The present invention has as its primary object the provision ofimproved illuminated display units.

A more particular object of the invention is to fulfill the need in theilluminated display field for effective vandal-resistant type displayunits.

In attaining the foregoing and other objects, the invention provides adisplay device component in the form of a plate bearing one or moredisplay indicia on one plate surface and having a passage extendingthrough the plate adjacent the display indicium. An integrallight-transmissive element is fixedly secured in the plate passage andhas a first lensed surface at one end adjacent the display indicium. Atits opposite end, the light-transmissive element defines both a secondlensed surface and a flat surface in abutting relation to a stepped partof the passage within the plate. The first lensed surface is convexrelative to the light-transmissive element and the second lensed surfaceis concave relative to the light-transmissive element. The element,comprised of a polycarbonate film which is highly resistant to impactdamage, is of dimension relative to the passage such that aninterference-fit exists therebetween. The element is accordingly notremovable by action thereon at the display surface, is not destructed byimpact and cannot be forced against an interior light source, therebyproviding a quite high degree of resistance to vandalism.

The foregoing and other objects and features of the invention will befurther understood from the following detailed description of apreferred embodiment of the invention and from the drawings wherein likereference numerals identity like parts throughout.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a display unit in accordance withthe invention.

FIG. 2 is an enlarged partial sectional view of FIG. 1 display unit aswould be seen from plane II--II of FIG. 1, the light-transmissive lensedelements in place.

FIG. 3 is a perspective view of a light-transmissive sheet for use inproviding light-transmissive elements for the FIG. 1 display unitshowing, in exploded fashion, an unlensed element provided from thesheet.

FIG. 4 is a front elevational view of the FIG. 3 unlensed element.

FIG. 5 is a front elevational view of a lensed element formed from theunlensed element of FIG. 4.

FIG. 6 is a sectional view of the FIG. 5 lensed element as would be seenfrom plane VI--VI of FIG. 5.

FIG. 7 is a bottom plan view of the FIG. 6 showing.

FIG. 8 is an enlarged partial sectional view of the FIG. 1 display unitas would be seen from plane II--II of FIG. 1 with its lensedlight-transmissive elements in place and with a source of illuminationsituated in operative position.

DESCRIPTION OF THE PREFERRED EMBODIMENT AND PRACTICE

Referring to FIG. 1, display unit 10, an elevator floor and directionindicator, includes a substrate 12, in the form of an aluminum orstainless steel plate, which has floor-indicating indicia 1-4,up-direction arrow indicium 5 and down-direction arrow indicium 6, allof indicia 1-6 typically being formed by indications in substrate 12which are painted in color contrasting with the color of the indentedsurface of substrate 12. Lensed light-transmissive elements 14a-f aresecured in substrate 12 in manner discussed below.

Substrate 12 has a first surface 16 (FIG. 2), forward in FIG. 1, and asecond opposite surface 18. Passages extend through the substrate andopen into surfaces 16 and 18, one such passage being shown in FIG. 2.This passage 20 has circular cross-section of dimension D1 in surface16, and is of lesser cross-sectional dimension D2 in surface 18, beingstepped therebetween.

FIG. 3 depicts a sheet 22 of a polycarbonate plastic material soldcommercially under the trademark LEXAN of General Electric Company. Asindicated, a flat unlensed cylindrical piece 24 is taken from sheet 22for preparation of each of lensed light-transmissive elements 14a-f.Piece 24 is inverted from its FIG. 4 orientation and is then gripped ina vise at its cylindrical sidewall 26, as shown by arrows 28 and 29 inFIG. 4. A deforming tool is now forcibly brought into contact with end30 of piece 24 and displaces end 30 into dimpled configuration, therebyproviding a first lensed end surface 32 (FIGS. 6 and 7) for piece 24,concave with respect to piece 24. The expanse of end 30 around surface32 remains flat and provides a stop or abut surface 32a. By reason ofthe physical properties of the material constituting piece 24, suchforcible contact of the tool with end 30 of piece 24 causes opposite end34 thereof to be displaced from flat configuration into arcuateconfiguration, thereby providing a second lensed end surface 36 forpiece 24, convex with respect to piece 24. Upon such working of piece24, the piece may be said to have a body portion extending betweenopposed lensed end surfaces.

Diameter dimension D3 (FIG. 4) of piece 24 is selected to be slightlylarger than cross-sectional demension D1 (FIG. 2) of the surface 16opening of passage 20, such that upon insertion of piece 24 into plate12, after the FIG. 5 tool working thereof, an interference fit relationexists as between piece 24 and substrate 12. Such insertion is done bydisposing piece 24, as worked, with lensed end surface 32 in facingrelation to opening 20. Lensed end surface 36 is now tapped with arubber hammer or the like until stop surface 32a of piece 24 bottoms oninterior surface or ledge 12a (FIG. 2) of substrate 12. Cylindrical axisdimension D4 of unlensed piece 24 is selected as not greater than andpreferably less than the dimension D5 of ledge 12a below surface 16 ofsubstrate 12 (FIG. 2). By this selection, the intersection surface 38 oflensed surface 36 and sidewall 26 of piece 24 is situated at or belowsurface 16 of substrate 12. This arrangement precludes access to anygrippable surface of piece 24, i.e., access is only to lensed surface36, since the rearward surface 18 of substrate 32, is in accessiblebased on the securement of substrate 12 to parent display unitstructure. Accordingly, the invention effects a vandal-resistant displayunit. In practice, it is found that efforts at gouging, marring,shattering or distorting the only accessible surface of piece 24 areineffective to destroy piece 24 in its sheltered disposition inaccordance with the invention and based on its material composition.

Referring to FIG. 8, piece 24, as worked, is shown installed in thedisplay unit as light-tranmissive element 14b, which receives lightinput from light source 40.

It is also found that the formation of the discussed plural lensedsurfaces in accordance with the invention accomodates the frequent needfor nonalignment of light sources and light-transmissive elements indisplay units. Thus, placement of light source 40 to the side of axis 42of piece 24, e.g., below or above its FIG. 8 disposition, is found toeffect superior issuance of light to a viewer of lensed surface 36 wherethe interior end of piece 24 is in lensed form as in the case of surface32, rather than in flat configuration in FIG. 4, prior to FIG. 5working.

As for the particularly effective composition of element 24, the LEXANpolycarbonate film is one having a tensile modulus of from 290,000 to300,000 pounds per square inch at room temperature, a tear initiation offrom 1150 to 1520 pounds per inch, and tear propogation of from 44 to 55pounds per inch.

Various changes to the foregoing particularly described embodiment maybe made without departing from the invention, as will be evident tothose skilled in the art. Accordingly, the foregoing discussion andparticularized showing are intended in an illustrative and not in alimiting sense. The true spirit and scope of the invention is set forthin the following claims.

I claim:
 1. A display device component comprising:a plate having apassage therethrough openings into first and second opposite surfaces ofsaid plate, said plate having a display indicium on said first surfacethereof; and an integral light-transmissive element fixedly secured insaid passage and having a first lensed surface adjacent said plate firstsurface, a second lensed surface adjacent said plate second surface, anda body portion extending between said first and second lensed surfaces,said passage being stepped in said plate, said body portion having flatsurface adjacent said second lensed surface in abutting relation to thestep of said passage, said first lensed surface being convex withrespect to said body portion and said second lensed surface being convexwith respect to said body portion.
 2. The invention claimed in claim 1wherein said passage includes a first extent of first cross-sectionaldimension and a second extent of second cross-sectional dimension lessthan thatof said first extent, said first passage extent opening intosaid plate first surface and said passage second extent opening intosaid plate second surface.
 3. The invention claimed in claim 2 whereinsaid body portion is of configuration generally in conformance with saidpassage first extent.
 4. The invention claimed in claim 3 wherein saidbody portion is fully resident in said passage first extent.
 5. Theinvention claimed in claim 4 wherein first lensed surface extends atleast in part outwardly of said plate first surface.
 6. The inventionclaimed in claim 4 wherein said second lensed surface is disposedinwardly of said plate second surface.
 7. The invention claimed in claim1 wherein said body portion is in interference-fit with said plate andfully resident in said passage.
 8. The invention claimed in claim 1wherein said body portion has a sidewall extending between said firstand second lens surfaces, the intersection surface of said first lensedsurface and said sidewall being disposed interiorly of said firstsurface of said plate.
 9. The invention claimed in claim 1 wherein saidflat surface of said body portion includes a portion adjacent saidsecond lensed surface in non-abutting relation with said step of saidpassage.